Fix Wasm limit and Safari instantiation (#1857)

test and fix wasm 4KB limit, as well as fixing Safari instantiation

src/features/wasm-load.js

@@ -12,7 +12,14 @@ systemJSPrototype.instantiate = function (url, parent) {
   .then(function (res) {
     if (!res.ok)
       throw new Error(res.status + ' ' + res.statusText + ' ' + res.url + (parent ? ' loading from ' + parent : ''));
-    return WebAssembly.compileStreaming(res);
+
+    if (WebAssembly.compileStreaming)
+      return WebAssembly.compileStreaming(res);
+    
+    return res.arrayBuffer()
+    .then(function (buf) {
+      return WebAssembly.compile(buf);
+    });
   })
   .then(function (module) {
     const deps = [];
@@ -34,7 +41,10 @@ systemJSPrototype.instantiate = function (url, parent) {
       return {
         setters: setters,
         execute: function () {
-          _export(new WebAssembly.Instance(module, importObj).exports);
+          return WebAssembly.instantiate(module, importObj)
+          .then(function (instance) {
+            _export(instance.exports);
+          });
         }
       };
     }];

test/browser/core.js

@@ -125,4 +125,12 @@ suite('SystemJS Standard Tests', function() {
       assert.equal(m.exampleExport(1), 2);
     });
   });
+
+  if (typeof WebAssembly !== 'undefined' && typeof process === 'undefined')
+  test('Loading WASM over 4KB limit', function () {
+    return System.import('fixtures/wasm/addbloated.wasm')
+    .then(function (m) {
+      assert.equal(m.addTwo(1, 1), 2);
+    });
+  });
 });